Xbox live Labs
If you choose to participate, each completed test rewards you with a cool Avatar item and a zero point achievement as a thank you for your contribution.
There are a total of three Avatar items and three zero point achievements that you can earn for each completed test, including a lab coat, brain helmet, and crazy mad scientist hair!
Xbox LIVE Labs runs from March 10-27 and is open to all Xbox LIVE members living in the United States. and uk see below ;)
How to get it free in the UK
Create a us profile (handy to have cause they get more free stuff than us)
nice guide here on how tohttp://www.xbox360achievements.org/forum/showthread.php?t=92807
if you don't want sign up for an email
you can get a windows live passport limited account with no email herehttps://accountservices.passport.net/ppnetworkhome.srf?vv=1000&mkt=EN-GB&lc=2057
Then sign in with your us profile on xbox go to the dashboard and go to my community click and download labs then sign out and log in with your usual profile
go to Quick Launch (pressing the guide button) and it's under Latest Downloads. click run it and leave it running to get the free avatar items.
Also once you get a us profile you can also download Aegis Wing for free and again us on any profiles on that console